Add releaseAndAbandonGpuContext bot

Bug: skia:5142
Change-Id: I35bd42d1a9da2293092a2f09aaaf523a0f36537a
Reviewed-on: https://skia-review.googlesource.com/14376
Commit-Queue: Eric Boren <borenet@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
5 files changed